Clazosentan in Preventing the Occurrence of Cerebral Vasospasm Following an Aneurysmal Subarachnoid Hemorrhage (aSAH)

Inclusion criteria

• . Male or female patients aged 18 to 70 years (inclusive) or male patients aged 45 to 70 (inclusive) or males aged 18 to 44 (inclusive) who are surgically or naturally sterile or can personally sign the core Informed Consent
• . Patients with a ruptured saccular aneurysm that has been confirmed by digital subtraction angiography (DSA) and for which clipping or coiling (endovascular obliteration) is possible.
• . Patients with a diffuse or localized thick subarachnoid clot on baseline CT scan. Measurements defining clot thickness and extension are as follows: Diffuse: Clot with long axis \>= 20 mm, or any clot if present in both hemispheres Localized: Clot with long axis \< 20 mm Thick: Clot with short axis \>= 4 mm Thin: Clot with short axis \< 4 mm
• . Start of screening within 48 hours post onset of aSAH clinical symptoms
• . World Federation of Neurological Surgeons (WFNS) Grades I-IV, and those Grade V patients who improve to Grade IV or less after ventriculostomy
• . In the case of multiple aneurysms, the aneurysm that has ruptured is identified with a high likelihood during the screening period
• . Women of childbearing potential with pre-treatment negative serum pregnancy test
• . Patient is able to start the study drug infusion within 56 hours after the rupture of the aneurysm, and the procedure option (clipping or coiling) must either be started within a maximum of 12 hours after the start of study drug infusion or should have been already performed

Exclusion criteria